Automobile audio system control units, usually referred to as “head units”, often include built in facilities for selectively receiving a multitude of broadcast radio signals, playing cassette tapes and, selectively playing a multitude of programs on a Compact Discs (CD). Such head units also include facilities for the user to select from among their different signal sources. The present invention makes it possible for such head units to be used to select additional signal sources, such as, for example, a portable MP3 player or the audio signal from a Digital Video Disc (DVD) without additional user interface facilities such as external switches, controls or any user control capability other than those already present on the car radio head unit. When so selected, the present invention directs the signal from an additional signal source directly to the speaker amplifier part of an audio system and then to the speakers. In this way the signal from the additional signal source is not subject to any effect or corruption that might otherwise be introduced by the head unit's intrinsic signal processing electronics. The present invention enables such additional selections by the use of either a special tape, a special CD, or by a local AM or FM radio signal modulator—a device that is able to introduce a locally supplied special signal in a way that can be selected and demodulated as an AM or FM radio signal—or by way of any signal media or source that can be selected with controls provided ppby the automobile's head unit.
Because audio systems, with their head units, are almost always supplied by the original automobile manufacturer as equipment that is an integral part of the automobile as it is manufactured, such Head Units are referred to as Original Equipment Manufacturer (OEM) head units. Such OEM head units are usually engineered to select from only a limited number of signal sources, most of which, if not all, are sources whose signals are developed and selected within the same modular unit. As a result, the signal selection circuits are not readily accessible to those who wish to apply such selection capabilities to other sources not provided for by the OEM's head unit.
Even though some OEM head units are in fact able to select from additional external sources, but in many cases such provisions will not ordinarily respond without corresponding digital remote control interface protocols. Such is the case with provisions for external CD changers, DVD players and Satellite radio receivers. Unfortunately, OEMs do not ordinarily release such digital remote control interface protocol details, and devices which are able to use such provisions are difficult and expensive to develop on account of the difficulty of reverse engineering such digital protocols. Even when such digital protocols are applied, additional difficulties are encountered when additional sources need to be selected over and above those protocols that are intended to handle. In such cases complicated sequences of user interaction are sometimes employed in conjunction with such digital protocols to expand upon the capabilities of the OEM head unit, as exemplified by the device described by U.S. Pat. Application No. 20040151327 to Ira Marlow and U.S. Pat. Application No. 20060093155 to David Fiori, Jr. and respectively.
Moreover, some such OEM head units provide for signal processing to compensate for the peculiarities of the speaker systems that are included with their cars. This can be a problem when different speakers are desired that do not exhibit the same, if any such peculiarities. In such cases it is desirable to process the signals in such a way as to remove such compensations and, if necessary, compensate for the peculiarities of the desired speakers instead.
In addition, the connection of external equipment to such OEM head units are often fraught with problems related to the pickup of interference such as automobile engine noises due mostly to the strong interfering magnetic fields and large ground currents created by the vehicle electrical system. In most cases such interference occurs as the result of extraneous noise currents flowing in connections cables that are commonly referred to as “ground loops”. As such, signal interface conditioning may also be included to avoid such interference and to enable the other aspects of the invention without compromise.
The present invention makes it possible to use those same user selection capabilities to select signals from additional signal sources. Using signal control facilities often included with such user interfaces, the present invention can also control signal processing parameters applied to the development of signals such signal development and handling systems are able to provide. In addition, the present invention also has utility in providing for the application of all kinds of signal processing to said signals in a manner that can respond to any or all of the signal processing parameters such user interfaces may be able to effect with their intrinsic capabilities. The present invention is also able to apply such signal processing according to such processing parameters with improved performance or utility. For example, said processing could then be performed with increased accuracy or increased power as compared to the intrinsic capabilities of the signal development and handling circuits. In addition, the present invention can also be applied to expand upon the number of parameters and processes that may be specified by said signal development and handling system interface and applied to said signals. Interactive systems that multiply the utility of this invention can also be implemented when this invention is coupled with any user feedback display capabilities—especially text display capabilities—the signal development and handling system may provide. Last, but not least, undesirable signal processing parameters may also be estimated and then processing performed to compensate for and to remove such undesirable processing when the provision of signals normally developed by said signal development and handling system, without such processing, is desired.
The present invention also makes it possible for signal processing to be applied to additional source signal with the same effects any signal normally developed by the automobile head unit would normally be subject to. For example, some automotive head units emphasize bass frequencies as a function of the speed of the automobile so that the bass part of the signal can be heard over road noises which increase with the speed of the vehicle. This same emphasis could be applied by virtue of the present invention to selected additional signal sources, except that the emphasis would be applied by circuits that are part of the present invention and not part of the head unit so that they can be designed to perform with higher audio accuracy and fidelity than the circuits provided in the automobile head unit for performing the same function. Such emphasis could also be reduced or enhanced in degree of effect since the processing occurs in the circuits that are part of the device that implements this invention which can have provisions for the configuration of such effects.
Such signal processing could also include processing that is performed by the automotive head unit in response to controls provided for the adjustment of signal processing parameters by the user. In this way the present invention would permit the user's specification of such signal processing parameters as signal volume, bass tone, and treble tone emphasis or de-emphasis to be applied to the additional signals without subjecting them to the effects of the head unit's own signal processing circuitry. In this way such processing can be performed upon the additional source signals with greater accuracy and audio fidelity than the automobile head unit may be able to provide.
The present invention can also be applied to control different kinds of processing or different functions in the vehicle.
The present invention can perform actions in response to controls provided by the automobile head unit for the adjustment of other signal processing parameters by the user. Last, but not least, and more specifically, the present invention can be applied to control parameters related to the selection of programs in the device that is selected with controls provided by the head unit for other purposes. For example, an auxiliary selection mode can be engaged which uses the volume control to specify the selection of a particular song in an MP3 device.
In this way the present invention makes it possible for the head unit's volume control to be used to select from among different songs on an auxiliary device, in addition to or instead of its normal use as a volume control. Other controls provided for in said head unit may also be used in such a fashion as may occur to someone of ordinarily skill in the art. Moreover, such capabilities could be multiplied and enhanced when coupled with the popular Radio Data Broadcast System (RDBS) capabilities now provided with many OEM FM capable head units. When FM radio modulation is used to deliver the special signal to the head unit, that same FM radio signal may also include textual information related to the operation of the interface by way of the RDBS capabilities. Such information can enhance, expand and multiply the utility of the invention as such textual displays can provide instructions or other types of guidance related to the user's operation of the present invention and the operation of auxiliary devices the present invention provides for.
Last, but not least, in instances where the normal signal is developed by the head unit with processing that has undesirable characteristics, the present invention can be applied to compensate for such undesirable characteristics when the automobile's head units own normal source signals are selected by the user. This is the case as many head units are designed to provide emphasis or de-emphasis at specific frequencies to compensate for the characteristics of the audio speakers used by the car manufacturer. When different speakers with characteristics different from those for which the compensation was intended are used in such audio systems, such compensation detracts from instead of improving the audio fidelity of the audio system. The present invention can also address this problem by processing signals developed by the automobile head unit in such as way as to remove such compensations. This can be accomplished by analyzing the signal processing applied to an appropriately generated special signal when the special signal is selected. Then, when normal signals are selected, compensations can be applied according to that analysis.